The studies proposed for the current year are: 1) to continue the yearly investigation of the mechanical properties of the lung (elastic recoil pressures, lung volumes), maximum expiratory flow-volume curves 2) to evaluate lung mechanics including frequency dependence of compliance and gas exchange in patients who had congenital lobar emphysema in early childhood 3) to apply our recently developed technique of obtaining maximal expiratory flow volume curves in infants to infants with evidence of chronic pulmonary disease and 4) to continue the investigation of the effects of high dose methyltrexate therapy upon lung function (particularly upon pulmonary capillary blood volume). BIBLIOGRAPHIC REFERENCES: Adler, S.M., and Wohl, M.E.B.: Flow-volume relationship at low lung volumes in healthy term infants. Pediat. Res. 10:457, 1976. (abst.). Strieder, D.J., Khaw, K.T., Gardida, A., Wohl, M.E.B., and Shwachman, H.: In-hospital treatment for chronic lung disease of cystic fibrosis: effect on lung function. Am. Rev. Resp. Dis. 113:46, 1976. (abst.).